Today, a radar device may be mounted on a motor vehicle in order to detect reflections from surrounding objects in order to implement functions of speed control and collision prevention, among other functions. In such a radar device it is required to obtain an azimuth angle in the form of a target bearing angle, a distance with respect to the object and a relative speed between the vehicle and the object.
For most vehicle radar applications it is important to measure the target bearing angle with very high precision. The angle accuracy of a radar system depends on fundamental parameters like modulation technique, antenna design, component tolerances, assembly precision and/or installation conditions. Furthermore, due to various environmental influences such as mechanical stress or bad weather, the angle estimation performance might suffer additionally. Some of those error sources show a random statistical distribution while others lead to a fixed angle offset. This fixed offset is the so called misalignment angle. Monitoring the misalignment angle is often an essential requirement in vehicle applications.
There are several approaches known which use vehicle dynamic information, e.g. vehicle speed, yaw-rate or steering angle, to verify trajectories of ground stationary targets. By comparing the expected path of an obstacle with the actual progression of the radar observations, one should be able to estimate the common bearing bias. The success of these techniques highly depends on the precisions of the vehicle dynamic data.
Addressing the above problems, U.S. Pat. No. 7,443,335 discloses angle error estimation for a vehicle radar based on relative speeds and reflections.
Furthermore, WO 2014/003615 discloses detection of radar detector misalignment by finding zero crossings for a derivative of a function describing the progression of detected target Doppler velocity as a function of detected target angle.
However, there is a need for finding a reliable and uncomplicated error compensation for a vehicle radar, which constitutes an object of the present disclosure.